Low power electromagnetic pump

Abstract

An electromagnetic pump comprising a housing having fluid receiving and pumping chambers in communication with an inlet and an outlet, respectively, an electromagnet carried by the housing external to the fluid chambers, and a barrier in the form of a thin diaphragm of fluid impermeable material which hermetically isolates the electromagnet from the fluid chamber. An armature in the housing is movable within a body of magnetically permeable material and has a pole portion located for magnetic attraction by the electromagnet and has a plunger portion in the pumping chamber for forcing fluid out of the chamber through the outlet. The armature is moved from a rest position through a forward pumping stroke when attracted by the electromagnet to force fluid out of the pumping chamber through the outlet, and the armature is moved by biasing spring in an opposite direction through a return stroke back to the rest position. The pump is made electrically and magnetically efficient by minimizing the total gap within the magnetic circuit, by having the pole face area relatively large on the armature pole portion, and by having the electromagnet include a coil or a core of relatively small diameter. A pump check valve closes the pump inlet when the armature is in the rest position and opens the inlet after the armature begins the forward pumping stroke.